Beta-(ortho-methoxy) phenyl-isopropyl 2-thenyl alkyl amines and salts thereof



Patented Oct. 10, 1950 1 BETA (ORTHO METHOXY)PHENYL -1sorBoPYL Z-THENYL ALKYL AMINES AND.

sAL'rs THEREOF Bichard V. Heinzelmann, Kalamazoo, Mich., as-

signor to The Upjohn Company, Kalamazoo, Micln, a corporation of Michigan No Drawing. Application January 21, 1949,

r Serial No. 72,080

8 Claims. (01. zoo-329) The present invention relatesto a novel series of compounds, having marked local anesthetic activity, whichmay be represented by the following formula:

CH3 R um derivatives are also useiulas surface-tension depressants, wetting agents, and the like. The provision of novelcompounds having the various above-mentioned utilities is a further object of the invention. Other objects will become apparent hereinafter. i

A study of the basic chemical structure of most known synthetic localanestheticsshows them to be tertiary amino-alkyl esters of amino-substituted aromatic acids. L For example, some representative known local anesthetics are beta-diethylaminoethyl (para-aminoL-benzoate, gammadibutylaminopropyl (pa r a amino) benzoate,

alpha, beta dimethyl gamma dimethylaminopropyl (paraamino) benzoate, and gamma- (methylpiperidino) -propyl (para amino) benzoate. Other local anesthetics of the prior art are alkyl esters of amino-substituted aromatic acids, e. g., ethyl and butyl (para-amino) -benzoates. In contrast to the foregoing well-known estertype anesthetics, the novelmethoxyphenyl isopropyl 2-thenyl amine derivatives of the present invention have an entirely different structure, and their strong local anesthetic activity is thus entirely unexpected.

The free bases of the present invention are mobile colorless topale amber liquids, slightly soluble in water, soluble in most common organic solvents such as methanol, ethanol, ether, chloroform, acetone, benzene and others, andform addition salts with mostacids. Representative acid addition salts ofthe amines which may be prepared are the formats, acetate, butyrate, benzolet manufacture.

2 ate, succinate, salicylate, citrate, tartrate, picrate, hydrochloride, hydrobromide, hydroiodide, solfate, phosphate, and the like. A preferred procedure for the preparation of the acid addition salts involves the admixture of anhydrous organic solutions of the amine and the acid in approximately stoichiometric proportions, which case the salt, which is insoluble in, the organic solvent, precipitatessubstantially as soon as it is formed. Alternatively, stoichiometric proportions of the acid and amine may merely be ad mixed and the solid saltobtained by evaporation to dryness. Other methods for preparingamine acid addition salts may also housed, and are known intheart. f f

Various other useful quaternary ammonium salts of the tertiary amines of the invention may also be prepared, as by mixing the amine with an alkyl halide, aralkyl-halide, or aryl sulfonic acid ester, heating the mixture, and thereafter separating the quaternary ammonium salt of the amine. Among compounds which may be employed in such manner to prepare the quaternary ammonium salts are methyl bromide, ethyl bromide, allyl chloride, cetyl bromide, myristyl bromide, lauryl bromide, benzyl chloride, benzyl bromide, ethyl (para-toluene) -sulfonate, and the like. As before stated, the quaternary ammonium salts thus produced are also useful as surface tension depressants and wetting agents.

When the compounds are desired to be employed as therapeutic agents, a preferred manner of oral administration is in the form of acid addition salts such as the hydrochloride, sulfate, citrate, or acetate, in which case the therapeutic agent maybe combined with excipients, diluents or lubricants according to known methods oftab- The amine salts may also be administered as an aqueous or other solution. When the free base is employed as the therapeutic agent, it may be administered by inhalation, as with a nebulizer. When employed as local anesthetics, any suitable method of application known in the art may be employed. l

In additionto being useful as local anesthetics, anticholinergics, antihistaminics, bronchodilators, and, in the case of certain quarternary ammonium salts, as surface-active agents, the compounds are useful intermediates in the preparation of other therapeutically useful compounds, viz., the corresponding orth'o hyclroxy substituted compounds. This conversion is accomplished, if desired, by demethylation, as with a strong acid and heat, evaporation, and isolation of the phenolicaminaeither as the hostess or a salt thereof according to conventional procedure.

The free base of the present invention may be prepared by adding Z-thenyl chloride to a sus pension of anhydrous sodiumearbonate in the particular beta (ortho-methoxy)phenyl-isopropyl alkyl amine, e. g., the methyl, ethyl, propyl, isopropyl, butyl, isobutyl, or tertiary-butyl amine, selected as starting material, while heating the mixture at a temperature of 120 to'150 degrees centigrade over a period of from one to four hours. The isolation is conveniently accon1- plished by pouring the reaction mixture into water, extracting with benzene, removing the solvent, and fractionally distilling to yield the free amine. Alternatively, the benzene solution may be treated by extracting with dilute aqueous acid, basifying the resulting aqueous solution, extracting with benzene, removing the solvent, dissolving the residue in ethyl acetate, adding hydrogen chloride or other acid in alcohol, e. g., isopropanol, thereto, and recovering the amine as its acid salt. Other conventional methods of preparation, isolation, and purification, both of the free base and of the salts thereof, are satisfactory.

As will be apparent to one skilled in the art, the tertiary amine produced by the preceding process is'de pendent upon the particular beta- (ortho-methoxy)phenyl-isopropyl alkyl amine used as starting material. Thus, if the alkyl group in the starting secondary amine is the methyl group, the product will be beta-(orthomethoxy) phenyl isopropyl 2 thenyl methyl amine or a selected salt thereof. Other tertiary amine products which may be obtained in the same manner, depending upon the particular starting material, include:

2 -thenyl 2 -thenyl 2-theny1 2 -thenyl 2-thenyl 2 -thenyl Z-thenyl Z-thenyl and acid addition and quaternary ammonium salts thereof, as disclosed in the foregoing.

The compound beta-(ortho-methoxy)phenylisopropyl isopropyl amine, an important intermediate in the preparation of one of the compounds of the present invention, is more fully described and claimed in my copending application Serial No. 72,028, filed January 21, 1949, now abandoned.

The following examples are given to illustrate the present invention, but are not to be construed as limiting.

Example 1.Beta- (ortho-methoa'y) phenylisopropyl isopropyl amine A solution of 8.25 grams of beta-(orthomethoxy)phenyl-isopropyl amine [J Am. Chem. Soc. 60, 465 (1938)], and 3.2 grams of purified acetone in 75 milliliters of absolute ethanol was added to 0.1 gram of Adams p atinum catalyst which had been activated by agitation in ethanol centigrade.

4 under an atmosphere of hydrogen. The suspension was shaken under a hydrogen pressure of about three atmospheres until the reduction was complete, which, in several experiments, usually required from one to four hours. The catalyst was then removed, the residual oil, when fractionally distilled, gave beta-(ortho-methoxy)- phenyl-isopropyl isopropyl amine, distilling at 126 degrees centigrade at a pressure of ten millimeters of mercury.

The hydrochloride of the free base was prepared by adding ethereal hydrogen chloride to an ether solution of the free base, and collecting the solid' hydrochloride after cooling overnight. After two crystallizations from ethanol, the beta- (ortho-methoxy) phenyl-isopropyl isopropyl amine hydrochloride melted at 1727-1737 degrees centigrade.

ANALYSIS Calculated for CmHzzONCl: C, 64.04 H, 9.10 N, 5. 74 Found: 63. 63 8. 8S 5. 72

Example 2. Beta- (ortho-methozry) phenyl-isopropyl Z-thenyl isopropyl amine Thirty-three and one-half grams of Z-thenyl chloride was added to a stirred suspension of 51.7

grams of beta-(ortho-methoxy) phenyl-isopropyl isopropyl amine and 44.0 grams of anhydrous sodium carbonate, heated to about 120 degrees centigrade over a period of about one hour. Heating and stirring were continued for an additional two hours, during which time the temperature was gradually raised to 150 degrees The reaction mixture was then cooled, water added, the aqueous suspension extracted with benzene, the benzene layer washed with water and then extracted with dilute hydrochloric acid. Three layers formed, an upper benzene layer, a middle aqueous layer, and a lower oily layer of undissolved amine hydrochloride. The benzene layer was discarded, whereafter the remaining layers were made alkaline with sodium hydroxide and extracted with benzene. The benzene extract was washed with water, the benzene removed, and the residue distilled under reduced pressure. There was thus obtained beta-(ortho-methoxy) phenyl-isopropyl 2-thenyl isopropyl amine, distilling at 151-158 degrees centigrade at a pressure of 0.05 millimeter of mercury, or at 162 degrees centigrade at a pressure of 0.08 millimeter of mercury.

The free base was converted to the hydrochloride salt by mixing solutions of the free base and hydrogen chloride in anhvdrous ether. The resulting oily precipitate, after crystallization from a mixture of ethanol, ethyl acetate, and ether, melted at 119-122 degrees centigrade.

ANALYSIS Calculated for CmHmONSCl: C, 63. 60 H, 7. 71 N, 4. 12 Found: 63. 56 7. 6O 4. 20

The picrate was also prepared, and when crystallized from methanol denatured ethanol, was found to melt at 127-128 degrees centigrade.

ANALYSIS Calculated for C24H2BOBN4SZ C, 54.12 H. 5.30 N, 10. 52 S, 6.02 Found: 54. 03 5. 33 10. 6. 09

Example 3. Beta- (ortho-methoay) phenyl-isopropyl Z-thenyl methyl amine Twenty-eight grams of 2-thenyl chloride was added to a stirred suspension of 35.8 grams of beta (ortho-methoxy) phenyl isopropyl methyl amine and 32.0 grams of anhydrous sodium carbonate, heated to about degrees centigrade the aqueous suspension extracted with benzene,

the benzene layer washed with water and then extracted with dilute hydrochloric acid. Three layers formed, an upper benzene layer, a middle aqueous layer, and a lower oily layer of undissolved amine hydrochloride. The benzene layer was discarded, the remaining layers made al1 aline with sodium hydroxide and extracted with benzene. The benzene extract was washed with water, the benzene removed, and the residue distilled under reduced pressure. There was thus obtained bcta- (ortho-methoxy) phenyl-isopropyl Z-thenyl methyl amine, distilling at 191-193 de grees centigrade at a pressure of 4.5 millimeters of mercury.

The free base converted to the hydrochloride salt by mixing solutions, in anhydrous ether, of the free base and hydrogen chloride. The resulting oily precipitate, after crystallization from a mixture of isopropanol, ethyl acetate, and ether, melted at 130.5-132 degrees centigrade.

ANALYSIS oaicuiatedsoromnaoNsoi: o,c1.s1 H,7.1l N,4.49 s,1o.2s Found: 61.58 6.78 4.56 10.46

The above hydrochloride, when crystallized from a mixture of ethanol and ethyl acetate, gave a second modification melting at 181.5-184 degrees centigrade.

wherein R is a lower-alkyl radical containing Heating and 6 up to and including four carbon atoms, and (23 acid addition and quaternary ammonium salts thereof.

2 An acid addition salt of beta-(ortho-meth- "nyl-isopropyl t IT M an CH, H N CH. S

wherein R is a lower alli'yl radical containing up to andincluding four carbon atoms.

tho-methoxy) phenyl-isopropyl 3. A hydrochloride addition salt of beta-(or- Z-thenyl alkyl I l CH2-CH-bf-CEb-Lgj (3H3 R wherein R is a lower-alkyl radical containing up to and including four carbon atoms.

5. Beta (ortho-methoxy)phenyl-isopropyl 2- thenyl methyl amine.

6. Beta (ortho-methoxy)phenyl-isopropyl 2- thenyl methyl amine hydrochloride.

amines of the formula:

7. Beta (ortho-methoxy)phenyl-isopropyl 2- thenyl isopropyl amine.

8. Beta (ortho-methoxy)phenyl-isopropyl 2- thenyl isopropyl amine hydrochloride.

RICHARD V. HEINZELMANN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,317,012 Woodruif Apr. 20, 1943 2,317,013 Woodrulf Apr. 20, 1943 OTHER REFERENCES Alles: J. Pharm. and Exp. Therapy, '72, 265-266 (1941) 

1. A COMPOUND SELECTED FROM THE GROUP CONSISTING OF (1) BETA-(ORTHO-METHOXY)PHENYL-ISOPROPYL 2-THENYL ALKYL AMINES OF THE FORMULA: 